The scope of the most powerful storm ever to make landfall was slowly revealing itself in the Philippines, where at least seven people were confirmed dead after Typhoon Haiyan swept the Pacific islands.

The typhoon generated nearly 200-mph winds as it rampaged through on Friday. By noon (11 p.m. ET Friday), its top winds had lessened to 110 mph - after having approached 195 mph at landfall Friday morning. Its center had cleared the country and was about 380 miles west of San Jose.

It was downgraded overnight from a "super typhoon," equivalent to a category 4 or 5 hurricane, to a typhoon.

Along the way, it cut off many of the country's lines of communication, leaving the extent of its damage a mystery overnight.

The government confirmed seven deaths and said four other people were missing. Four people were killed Thursday and Friday as the storm lashed the islands, the national disaster agency said Friday, and early Saturday, the official Philippine News Agency confirmed that three others were killed in Coron in northern Palawan.

Hundreds of homes were flattened and almost 800,000 people were evacuated to emergency shelters as Haiyan triggered mudslides, flash flooding and a storm surge with waves of up to 30 feet Friday.

But forecasters and government officials said a much more devastating toll could emerge in the hours and days to come. Because the Philippines is made up of more than 7,000 islands — more than 2,000 of them inhabited, with their own local authorities and infrastructures — it typically takes two to three days for full reports to reach rescue agencies.

"It is the most powerful storm ever to make landfall," Michael Palmer, lead meteorologist for The Weather Channel, told NBC News. "It is as strong a typhoon as you can get, basically," with winds able to "obliterate poorly constructed homes."

Some of the worst-hit areas were still recovering from a deadly 2011 storm and a 7.2-magnitude earthquake last month, and "thousands of people are likely to be left without food, shelter and water," said Bernd Schell, the Philippines representative for the International Federation of Red Cross and Red Crescent Societies.

"This is a double blow for the survivors of the earthquake in Bohol and Cebu, who were already struggling to get back on their feet," he said.

In a statement, U.S. Secretary of State John Kerry said the U.S. embassies in the Philippines and Palau were in close contact with the government and were ready to provide any assistance. The European Union said a humanitarian aid team was already in the country to assess what help was needed.

Dale Eck, director of The Weather Channel's global forecast center, said the strongest winds had lingered over the Philippines only for two to four hours, meaning "the duration of the extreme winds was short."

More than 100 coastal homes were flattened, and landslides destroyed houses in the hills in Southern Leyte province, Gov. Roger Mercado told DZBB radio of Manila.

"We lost power, and all roads are impassable because of fallen trees," he said. "We just have to pray."

Palmer of The Weather Channel said gusts of 220 mph had been recorded. "That is the equivalent of EF4 tornado winds — even EF5," he said. "You would not be able to stand up. It would knock you off your feet and blow you away."

Even so, Palmer warned that the storm surge presented the most danger. "Usually, that's what causes the most death and destruction," he said.

The storm surge flooded the town of Palo in Leyte province under 10 feet of water, PNA said Saturday. It said emergency officials were working to confirm local television reports that about 20 people drowned.

Transportation was deadlocked, with roads across the country rendered impassable.

Four airports remained closed and 118 domestic flights were canceled, the Civil Aviation Authority said Saturday. Almost 3,400 passengers on 76 sea vessels were stranded in port as they tried to ride out the storm, the national disaster agency said.

At least 14 crew members had to be rescued from two cargo vessels in Guindulman, the national news network ABS-CBN reported.

Meanwhile, evacuations were already under way in Vietnam and Laos, where Haiyan was projected to hit next. Meteorologists in Vietnam said it could be the country's strongest storm ever.

Alexander Smith and Elizabeth Chuck of NBC News contributed to this report.